1. Field of the Invention
The invention relates generally to a semiconductor device and a method of manufacturing the same, and more particularly to, a gate structure in a flash memory cell and a method of forming the same, and a method of forming a dielectric film.
2. Description of the Prior Art
An ONO dielectric film of the flash memory device, i.e., a dielectric film of a structure on which an oxide film, a silicon nitride film and an oxide film are sequentially stacked, is used as an insulating film between a floating gate for storing data when the memory device is driven and a control gate. Meanwhile, methods for increasing the coupling ratio include increasing an electrode area of the floating gate, reducing a thickness of the insulating film between the floating gate and the control gate, and using the dielectric film of a high dielectric constant. In DRAM (dynamic random access memory) devices, in case of the capacitor, the electrode area of the capacitor could be increased by applying a 3-dimensional structure of a cylinder shape or a pin shape to the capacitor. On the other hand, in case of the flash memory device, there is a structural problem that the 3-dimensional structure is difficult to be applied to the floating gate. Currently, the method of reducing the thickness of the dielectric film reaches a limitation in reducing the thickness. Also, in case of the method of using the dielectric film of a high dielectric constant, there is a problem that a new dielectric material must be developed.